Review: Crystalline Inclusion Complexes as Media of Molecular Recognitions and Selective Reactions

Abstract

Hexaol host compounds that include guest molecules in a maximum host-to-guest ratio of 1:6 were prepared. The aromatic hexaol host, hexahydroxytriphenylene, was found to form a chiral inclusion-complex crystal upon complexation of an achiral guest molecule. Some interesting and important optical resolutions of rac-guests by inclusion with a chiral host are described. When chemical reaction and inclusion in a water suspension medium are combined, new economical and ecological methods of the preparation of optically active compounds can be established. When photochemical reactions are performed on the guests of an inclusion-complex crystal formed with a chiral host, enantioselective reactions occur and optically active products can be obtained. Several successful reactions are described. Crystalline inclusion complexes of guest compounds with various artificial hosts are useful as media for the following molecular recognitions and selective reactions in the solid state. Manuscript received: 4 October 2001. Final version: 13 November 2001.